Subgrade reaction coefficient is commonly considered as the primary challenge in simplified seismic design of underground structures. Carrying out test is the most reliable way to acquire this intrinsic soil property. Owing to the limitations of experimental cost, time consumption, soil deformation mode, size effect, and confined condition, the existing testing methods cannot satisfy the requirements of high-precision subgrade reaction coefficient in seismic design process of underground structures. Accordingly, the present study makes an attempt to provide new laboratory testing methods considering realistic seismic response of soil, based on shaking table test and quasistatic test. Conventional shaking table test for sandy free-field was performed, with the results indicating that the equivalent normal subgrade reaction coefficients derived from the experimental hysteretic curves are reasonable and verifying the deformation mode under seismic excitation. A novel multifunctional quasistatic pushover device was invented, which can simulate the most unfavorable deformation mode of soil during the earthquake. In addition, the first successful application of an innovative quasistatic testing method in evaluating subgrade reaction coefficient was reported. The findings of this study provide preliminary detailed insights into subgrade reaction coefficient evaluation which can benefit seismic design of underground structures.

中文翻译：

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地下工程领域抗震设计中路基反应系数的室内试验

路基反应系数通常被认为是简化地下结构抗震设计的主要挑战。进行测试是获得这种土壤固有特性的最可靠方法。由于实验成本，时间消耗，土壤变形模式，尺寸效应和约束条件的限制，现有的测试方法不能满足地下结构抗震设计过程中高精度路基反应系数的要求。因此，本研究试图提供一种基于振动台试验和准静态试验的考虑土壤真实地震响应的新型实验室试验方法。进行了沙地自由场的常规振动台测试，结果表明，从实验滞回曲线推导出的等效法向路基反应系数是合理的，并验证了地震激励下的变形模式。发明了一种新型的准静态推覆装置，可以模拟地震过程中最不利的土壤变形模式。此外，还报道了一种创新的准静态测试方法在评估路基反应系数中的首次成功应用。这项研究的发现为路基反应系数的评估提供了初步的详细见解，这有助于地下结构的抗震设计。可以模拟地震过程中最不利的土壤变形模式。此外，还报道了一种创新的准静态测试方法在评估路基反应系数中的首次成功应用。这项研究的发现为路基反应系数的评估提供了初步的详细见解，这有助于地下结构的抗震设计。可以模拟地震过程中最不利的土壤变形模式。此外，还报道了一种创新的准静态测试方法在评估路基反应系数中的首次成功应用。这项研究的发现为路基反应系数的评估提供了初步的详细见解，这有助于地下结构的抗震设计。